Various types of high pressure sluice knife gate valves are known in the art. These types of knife gates can be divided into two different designs, including an open blade type knife gate and a bonneted structure type gate.
An open blade type knife gate necessitates the use of a seal around the blade. Because a packing type seal is normally used in this gate, the resultant design is limited to applications where fluid pressure is less than 150 PSIG.
Bonnet structures are attached to the knife gate as a separate element. The use of a bonnet eliminates the need for a seal around the blade and relies instead on a seal around the cylindrical actuator rod. This type of seal arrangement is suitable for applications where fluid pressure is 300 PSIG and higher.
This invention relates to an improvement over all the known prior art knife gate valves. It is a primary object of this invention to provide a gate valve wherein the principle design has the body itself carrying the features of the bonnet. This allows the valve to:
(1) Contain the fluid pressure without the use of a special seal around the blade; PA0 (2) Minimize the axial dimension of the valve body; PA0 (3) Minimize stresses in the valve body; PA0 (4) Operate in applications where fluid pressure is 300 PSIG and higher; PA0 (5) Operate with a replaceable liner comprised of two indentical halves. PA0 (1) Seals the components attached to the valve, including pipe flanges and valve actuating devices. PA0 (2) Guarantees separation of the fluid from the valve body in both the open and closed positions.
The liner as shown in FIG. 1 provides two new features:
The latter feature is important in applications wherein the chemistry of the fluid is damaging to the valve body material and also wherein environmental protection is a concern.